This section provides background information related to the present disclosure which is not necessarily prior art.
Known systems used to control operations of aluminum processing baths can include electrical circuits closed when a crust breaking tool creates an aperture by breaking through the hardened upper crust formed on the bath and either encounters a layer of alumina, or the molten layer of aluminum below the layer of alumina. The aperture formed through the crust is necessary to permit feeding new alumina material into the bath. When the electrical circuit closes, a signal is created which directs the crust breaking tool to retract from the crust layer. An example of such a system is disclosed in U.S. Pat. No. 6,649,035 to Horstmann et al. A drawback of such systems occurs when crust material forms on the crust breaking tool or corrosive effects of the bath prevent completion of the electrical circuit.
In this situation, the crust breaking tool can remain in the bath for an undesirable length of time which can damage the crust breaking tool, or render the detection system inoperative. In these situations, the subsequent feeding of new alumina material into the bath can be hindered, or the system may be unable to identify how many feed events have occurred, thus leading to out-of-range conditions in the bath. A further drawback of known control systems is the crust breaking tool is generally driven by a system using high pressure air. The longer the crust breaking tool is suspended or extended into the bath, the greater volume of high pressure air is required, which significantly increases operating costs of the system due to the size and volume of high pressure air system requirements, which increases the number of air compressors and air dryers required for operation.